The present disclosure relates to a speaker magnetic circuit.
As described in Japanese Patent Laid Open Publication No. H08-9494 (Patent Literature 1), a magnetic circuit of a general external magnetic-type speaker includes a top plate, a magnet, and a yoke. From the center of the yoke, a center pole protrudes. Between an inner circumferential surface of the top plate and an outer circumferential surface of the center pole, a magnetic gap is formed. In the magnetic gap, a voice coil wound around a voice coil bobbin is arranged.
Japanese Patent Laid Open Publication No. 2009-124200 (Patent Literature 2) describes that, in order to enhance heat radiation of the speaker, air from a diaphragm is guided to a cover that covers the magnetic circuit, and the magnetic circuit is cooled. Japanese Patent Laid-Open Publication No. 2006-60443 (Patent Literature 3) describes that a heat radiating member is installed on the top plate to thereby cool down the top plate. Japanese Patent Laid-Open Publication No. 2005-341475 (Patent Literature 4) describes that heat radiating components are installed on and under the top plate.
In accordance with such technologies described in Patent Literatures 2 to 4, heat from the voice coil is drawn indirectly, whereby the voice coil can be cooled down.